Pituitary AdenomaBy Dr mazhar ali
Did you know??Robert Wadlow was the tallest recorded man on earth at a height of 8 ft 11 in. His astounding height was the result of a pituitary tumor
Anatomy Located immediately under the hypothalamusRests on the Pituitary fossa (sella turcica)Comprised of two lobes; anterior (adenohypohpysis) and posterior (neurohypophysis)The lobes are separated by an intermediate lobe
FunctionThis organ is part of the endocrine systemOnce thought of as the master gland the pituitary gland is actually controlled by the hypothalamusSends many
hormones to glands throughout the body
PITUITARY ADENOMAPituitary adenomasare a collection of tumors that arise from thepituitary gland. They are the most common cause ofOptic chiasm compression.Ophthalmologic pathology typically involvesVisual field defects, although less commonly patients may also haveOcular motility deficitsand/orDiplopia, certain forms ofNystagmus, signs and symptoms ofIncreased intracranial pressuredue to mass effect,Optic atrophy.
- CLASSIFICATION Size,Macroadenomas: 10 mmMicroadenomas:
SymptomsHeadachesVision ProblemsVisual DisturbancesNauseaVomiting
PITUITARY ADENOMA(BASOPHIL)Basophil tumours secrete ACTH and cause Cushing disease (Cushing syndrome refers to the clinical picture due to any cause of increased blood cortisol).
SIGNs a Obesity may be generalized or classically involve the trunk, abdomen and neck (buffalo hump). b The face is swollen (moon face) females may be hirsute c The skin is thin and susceptible to bruising. Purple striae may be seen Hyperpigmentation may develop with ACTH-dependent Cushing syndrome d Other features depression/psychosis, osteoporosis, slow wound healing and proximal myopathy.
Ophthalmic featuresBitemporal hemianopia is uncommon with secreting pituitary adenomas, which tend to present with systemic features of hypersecretion,
As opposed to non-secreting pituitary tumours, which tend to present with chiasmal compression
COMPLICATIONinclude hypertension, diabetes, pathological fractures and acute necrosis of the femoral head
INVESTIGATIONIn Cushing syndrome are targeted at first establishing the presence of elevated cortisol levels then identifying the underlying cause (unless iatrogenic); they are best undertaken by an endocrinologist.
TREATMENT a Surgical removal of pituitary adenoma or adrenal secreting tumour. Ectopic foci of ACTH secretion may also be amenable to excision.
b Medical suppression of cortisol secretion with metyrapone or aminoglutethimide.
PITUITARY ADENOMA(ACIDOPHILIC)Acidophil tumours cause gigantism in children and acromegaly in adults.
Acromegaly is caused by excessive growth hormone (GH) occurring during adult life, after epiphyseal closure and is almost invariably due to a secreting pituitary acidophil adenoma (hypersecretion of growth hormone in childhood, prior to epiphyseal closure, results in gigantism).
SIGNs a Skin. Hyperhidrosis, acne and hirsutism in females. b Face thick lips, exaggerated nasolabial folds, prominent supraorbital ridges Enlargement of the jaw with dental malocclusion
c Enlargement of the head hands, feet, tongue and internal organs.
Ophthalmic featuresa Common. Bitemporal hemianopia and optic atrophy. b Rare. Angioid streaks and see-saw nystagmus of Maddox.
INVESTIGATIONThe diagnosis may be confirmed by measuring GH levels in response to an oral glucose tolerance test.
Normal individuals manifest suppression of GH levels to below 2mU/L. However, in acromegaly, GH levels do not fall, and may paradoxically rise.
TREATMENTTreatment options include Bromocriptine (a long-acting dopamine agonist), Radiotherapy (external beam or by implantation of yttrium rods in the pituitary) and Trans-sphenoidal hypophysectomy.
PITUITARY ADENOMA(CHROMOPHOBE)Chromophobe adenomas may secrete prolactin and are referred to as prolactinomas
in men they cause hypogonadism, impotence, sterility, decreased libido, and occasionally gynaecomastia
Chromophobe adenoma is the most common primary intracranial tumour to produce neuro-ophthalmological features.
PRESENTATIONHead ache due to involvement of pain-sensitive fibres in the diaphragma sellaeVisual field defects depend on the anatomical relationship between the pituitary and chiasm. If the chiasm is central, both superotemporal fields are affected first, as the tumour grows upwards and splays the anterior chiasmal notch, compressing the crossing inferonasal fibres The defects then progress into the lower temporal fields. As tumour growth is often asymmetrical, the degree of visual field loss is usually different on the two sides. Patients may not present until central vision is affected from pressure on the macular fibres.
Optic atrophy is present in approximately 50% of cases with field defects caused by pituitary lesionsExtensive loss of the temporal visual field in both eyes can disrupt sensory fusion, decompensate a phoria or cause problems with near vision. Postfixation blindness refers to the presence of a blind area distal to the fixation point.Miscellaneous features include diplopia as a result of lateral expansion into the cavernous sinus and involvement of ocular motor nerves and, rarely, see-saw nystagmus
Special investigations of pituitary adenomasMR demonstrates the relationship between a mass lesion and the chiasmCT will demonstrate enlargement or erosion of the sellaEndocrinological evaluation All patients suspected of having a pituitary adenoma should have assays of serum prolactin, FSH, TSH and growth hormone
PreventionThere are no known ways to prevent pituitary cancer, but there are ways to lower your chances of getting any kind of cancer, and to kill it early if you do get cancer. Such methods include: Know your familys health history, and take note of any signs that could be a sign of cancer.Eat well, and stay active.Avoid extensive exposure to harmful substances such as chemicals and even the sun.